A great many proposals have been made hitherto for making ground or wall coverings from wooden panels or planks.
Thus, the document DE 21 23 206 describes a covering consisting of wooden panels or planks which are fixed against a surface, side-by-side, leaving a space between the said surface and the underside of the covering.
According to this document, the spacing and the fixing of the elements of the covering is obtained by means of a pair of elements distributed, the one over the whole surface of the planks, the other against the surface to be overlaid.
Such fixing elements call upon clipable cones disposed against the entire surface to be overlaid and the underside of the covering.
Such a fixing means which is envisaged for use for making interior parquet floors cannot, in any circumstances, allow its use to be contemplated for making exterior wooden floors or terraces on account of the fact that the main problem which arises in such circumstances is that of the durability of the constructed works which are subjected directly to inclement weather and the sun.
Indeed, wood being a biopolymer, it is by definition biodegradable, especially as regards the cellulose and hemicellulose compounds, since these compounds are in fact polysaccharides (chemistry of sugars), and therefore offer very little resistance over time, and are much coveted by microorganisms of the xylophagous type.
Accordingly, if good outdoor durability of the wood is required, it is vital to comply with two essential conditions, namely not to have direct contact with the ground and not to allow water (rain or similar) to stagnate or remain trapped on or in the wood.
Moreover, it is obvious that the durability will also depend on the species of wood used and also on any treatment, for example chemical treatment in a high-pressure autoclave, which increases durability.
Lastly, in the case of terraces or other external works, it is vital to achieve a structure which makes it possible to support the passage of considerable loads, such as for example an urban cleaning machine.
The solution described in the aforesaid patent does not in any event make it possible to solve such problems.
Indeed, in this document, the fixing elements call upon clipable cones disposed against the entire surface to be overlaid and the underside of the covering.
If such a fixing means is envisaged for a covering intended to be used outdoors, during such use, all of the cone surfaces can fill with water, and this will cause degradation of the wooden structure.
Additionally, the solution of this document does not in any event allow ventilation of the lower layers of the covering.
Moreover, the use of cones distributed over the entire surface demands deployment on a perfectly flat surface and does not allow any adjustment.
Lastly, the solution described in this document can be regarded as a non-structural solution and would therefore not be able to support the passage of considerable loads, such as for example urban cleaning machines.